The present invention relates to the on-contact, instantaneous disinfection of water, and more particularly to the use of synergically stabilized, mixed form halogenated and/or interhalogenated vinylpyridine resins for disinfecting water.
Several techniques employing resins are known for killing bacteria in water. The usual method involves treating the water with resins that provide halogen residuals such as I.sub.2, Br.sub.2, and Cl.sub.2 for disinfection. Several methods involve the use of polyhalide anion exchange resins. Still another water disinfecting technique involves the use of an anion exchange resin loaded with insoluble triiodide ions (I.sub.3.sup.-). The following patents show examples of these techniques: U.S. Pat. Nos. 3,316,173; 3,425,790; 3,436,345; 3,462,363; 3,565,872; 3,817,860; 3,923,665; 4,187,183; 4,190,529; and 4,420,590.
Resins in accordance with the techniques noted above have the potential for releasing halide and polyhalide ions and do not produce an optimum halogenhypohalous acid mixture, and, as such, diminish their bactericidal efficiency. The resins of U.S. Pat. No. 3,565,872, though not made from anion exchange resins, also have these disadvantages, as well as the disadvantage for the potential for promoting resin decomposition in aqueous media, such as with the Cl.sub.2 --, Br.sub.2 --, and the BrCl--forms. Further, none of the above anion exchange resins generate hypohalous acid when treating water high in total dissolved salts with the exception of U.S. Pat. No. 4,187,183 which releases only very low levels of hypoiodous acid (less than 0.22 ppm HOI) under such circumstances. Hypoiodous acid is desirable since it is more bactericidal and more virucidal than iodine (I.sub.2). Heretofore, significant levels of hypoiodous acid have had to be generated by either an iodinated anion exchange resin in combination with a scavenger system as in U.S. Pat. No. 4,187,183 or by adding an extraneous oxidant such as a chloramine as in U.S. Pat. No. 3,163,716 and U.S. Pat. No. 3,161,588. The interhalogenated resins in U.S. Pat. No. 3,565,872 produce hypohalous acids but not in an optimum disinfecting mixture with a corresponding halogen, e.g., I.sub.2 --HOI, Br.sub.2 --HOI, or Br.sub.2 --HOBr.
Therefore, a resin which provides for single pass, on-contact instantaneous disinfection, releases an optimum mixture of disinfecting levels of halogen and hypohalous acid without halide and polyhalide release, and which provides for long term resin stability in aqueous medium would be a significant improvement in water treatment technology.
Accordingly, it is an object of the present invention to provide synergistically stabilized, mixed form halogenated and/or interhalogenated polymeric, vinyl pyridine resins for single pass, on-contact instantaneous disinfection of water. It is another object to provide such resins as disinfectants capable of producing optimum disinfecting mixtures of halogen and hypohalous acid (e.g., HOBr or HOI through hydrolysis of the interhalogen, or through reaction of one halogen or interhalogen with another halogen) for universal disinfection against bacteria, viruses, and amoebic cysts. Still another object of the invention is to provide such resins for producing halide- and polyhalide-free effluents when treating water relatively high in salt content. Yet another object of the invention is to provide such resins that possess long term stability in an aqueous medium.
In accordance with these objects, granular or bead form, polymeric vinylpyridine resins which have been cross-linked with divinylbenzene, divinylpyridine, or other conventional crosslinking agent and which contain the pyridyl functional group covalently bonded to the vinyl polymeric backbone by the pyridyl No. 2 or No. 4 carbon are treated with a mixture of halogens and/or interhalogens to provide a media for disinfection of bacterially contaminated water. With the present invention, depending on the degree of loading of halogens and/or interhalogens on the vinylpyridine resin, instantaneous, single-pass flow-through disinfection can be achieved and a residual halogen and hypohalous acid (HOBr or HOI) is produced. If the residual halogen and hypohalous acid are to be reduced or removed, a simple follow-up scavenger column or bed of activated carbon can be employed.
The combined features of non-ionic complexation of the mixture of halogens and/or interhalogens with the pyridyl functional group and the hydrolysis of the interhalogens and/or reaction of one halogen or interhalogen with another halogen within the resin matrix precludes the ion exchange of halide ions (I.sup.- and Br.sup.-) and polyhalide ions (I.sub.3.sup.-, Br.sub.3.sup.-, I.sub.2 Cl.sup.-, etc.) which can occur in the previous state of the art disinfecting resins when they are challenged with water containing a high level of total dissolved salts. Minimizing the halide and polyhalide content of the effluent water provides for more potent disinfecting action and for a more physiologically acceptable potable water as pointing out in U.S. Pat. No. 4,420,590. The problem of excess halide (greater than 5-10 ppm) and polyhalide exchange from resins when treating water high in total dissolved salts can occur with resins prepared in accordance with the previous state of the art such as those resins in U.S. Pat. Nos. 3,565,872; 3,187,806; and 4,187,183. This problem is eliminated and does not occur with resins prepared in accordance with the present invention.
Because of the non-ionic complexation in the present invention, no iodide or bromide salt (e.g., KI or KBr) is needed in the preparation, thereby maximizing the disinfection efficiency of the total halogens and interhalogens. For example, in the Br.sub.3.sup.-, form of polyhalide resin such as in U.S. Pat. No. 3,462,363, one-third of the halogen is wasted just to provide for binding the negatively charged tribromide ion (Br.sub.3.sup.-), to the positively charged anion exchange resin.
Resins prepared in accordance with the present invention may be employed for swimming pool disinfection, emergency water disinfection kits, and small scale drinking water treatment systems with appropriate scavenging systems, as well as other applications where water disinfection is desired.
The unique features of this invention solve problems apparently not recognized in the prior art. These unique features are not characterized by the vinylpyridine-based polymers alone, but by their mixed form halogen and/or interhalogen molecular addition reaction products which, heretofore, have never been prepared and tested. Neither have the on-contact, bactericidal action and heretofore unknown synergistic stability of the mixed form resins been demonstrated; nor has their ability to produce effluents containing optimum mixtures of halogen and hypohalous acid been demonstrated. The synergistic stability of the mixed form resins, though not fully understood, is believed to be due to an inherent reduction-oxidation buffering phenomenon or "redox" equilibria occurring within the resin matrix and is believed to occur to some degree in all of the mixed form resins. Similar redox equilibria is defined by Light (T. S. Light, Anal. Chem., 44, 1038 (1972)) and examples are given by Lambert et al. (Anal. Chem., 47, 915 (1975)) and Black and Whittle (J-AWWA, 59, 607 (1967)).
The disclosures of the prior art, including U.S. Pat. No. 3,565,872, fail to provide any teachings of the present invention, and the advantages of the present invention as described above are, as a whole, believed to be unobvious and of a surprising and unexpected nature to one skilled in the art.